I think that your understanding is incomplete, she was not engaged to any one so the punishment is 50 pieces of silver and a life time of hell being married to the woman of your nightmares. Incapacitated or not.
Also, in times past her behavior would have resulted in her being ostracized from society for generally acting like a whore. Virtuous women even 50 years ago did not do what this poor excuse for a woman did so she deserves all the scorn she gets (which is not that much unfortunately).
You should probably reread Deuteronomy and think for a bit. A girl taken by force is never required to marry her attacker. The biblical example is a girl taken in a field where her cries would not be heard. This is analogous to being unconscious and unable to cry out. The fact that she was drunk to unconsciousness only proves that no consent was given.
Just as God looks after children and fools, He intended His Law to do the same.